OverviewSome people have more bones in their feet than others. Actually, it?s not all that uncommon to have extra bones in the feet. These extra bones area called accessory bones. The navicular bone, one of the small bones located at the instep or arch of the middle of the foot, is an example of an extra bone people are born with. It?s called the accessory navicular bone. During the maturation process, the navicular and the accessory navicular never fuse into one solid bone, but remain connected by fibrous tissue or cartilage. It is estimated that 4-14% of the population are born with an accessory navicular bone.

CausesIt is commonly believed that the posterior tibial tendon loses its vector of pull to heighten the arch. As the posterior muscle contracts, the tendon is no longer pulling straight up on the navicular but must course around the prominence of bone and first pull medially before pulling upward. In addition, the enlarged bones may irritate and damage the insertional area of the posterior tibial tendon, making it less functional. Therefore, the presence of the accessory navicular bone does contribute to posterior tibial dysfunction.

SymptomsMany people with an accessory navicular do not experience symptoms, however some may notice a bump and/or swelling on the inside of the foot just above the arch. They may also experience pain in the middle of the hepatitis c foot pain; kathleenwinborne.hatenablog.com,, particularly with physical activity.

DiagnosisDiagnosis starts by speaking with the patient about symptoms. The physician will look at the foot and examine it for signs of an accessory navicular. By putting pressure on the area, the doctor may determine its presence simply by the presence of pain. The muscle, joint, and the overall structure of the foot may be considered, as well as the way in which the patient walks. If a diagnosis of accessory navicular syndrome is made, an X-ray or MRI may be ordered to confirm diagnosis.

Non Surgical TreatmentTreatment options for a painful accessory navicular can include anti-inflammatory medications, rest, arch support structures in the shoe, or use of a cast or splint. Severe cases may require surgery.

Surgical TreatmentIf conservative care does not alleviate the problem then surgical intervention should be considered. The most common procedure for this condition is known as the Kidner procedure where a small incision is made over the navicular bone. The accessory navicular is identified and dissected free from the posterior tibial tendon. The posterior tibial tendon is then reattached to the remaining navicular bone.
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